Detector fabrication techniques are currently being examined in order to develop PbSnTe photodiodes which are stable, have high quantum efficiencies and which have resistance-area products large enough for efficient signal injection into CCDs. Devices with these characteristics are required for the future development of focal planes, operating in the 8-14 micrometer range, containing at least 1000 detectors interfaced with silicon signal processors. Prior results have been reported for PbSnTe infrared detectors fabricated by using indium as the dopant to form shallow n-p junctions. See "Planar Pb.sub.0.8 Sn.sub.0.2 Te Photodiode Array Development at the Night Vision Laboratory," by P. LoVecchio, et al, Infrared Physics, Vol. 15, Nov 75, pp 295-301. Detectivities of 2.times.10.sup.10 cm.sqroot.Hz/w ("w" being watts) and RA products of 0.4 ohm. cm.sup.2 were obtained using indium, where R is the zero-bias impedance of the diode and A is the sensitive area. These RA product values are much too low for efficient signal injection into CCDs. In addition, the 100.degree. C. vacuum bake temperature required for good vacuum integrity is approximately equal to the diffusion temperature of indium, and there were some indications that the indium devices tended to be unstable when exposed to temperatures of the order of 100.degree. C.